High-voltage discharge while car is not used

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Dec 23, 2016
My 2016 SEL got a new set of tires for Christmas so I had to reset the tire pressure monitor setting. About the same time this was done I started to notice a loss of range while the car was parked in the garage. The guess-o-meter dropped 5-10 miles a day. Power was off and there were no visible or audible signs of any activity. Re-charging times were normal, indicating that it really was a discharge and not a malfunction of the range indicator. The only thing I could think to do was to reset the factory settings, and to my relief this solved the problem. Not sure if it was caused by the tire pressure reset or if that was a coincidence.

Any ideas what might have caused this, or what was draining the high-voltage battery?
1. Was the car locked while sitting unused?
2. What do you mean "charging times were normal" - please give us some data?
3. How did you reset to factory settings?
4. What was the State of Charge (SoC) at the beginning and end of the dwell time?
5. What was the ambient temperature at the beginning and the end of the dwell time?
6. Were you communicating to the car via the cell phone app or via the web interface during the dwell time?

I find it hard to believe the HV battery was being drained. I have left my car sitting for weeks at a relatively constant ambient temperature and saw no change in SoC, and I have done this three or four times. If you locked the car, it goes into a deep sleep mode and uses essentially zero energy.
1. the car was not locked most of the time, just sitting in the garage and getting charged when necessary
2 and 4. I did not keep close track of numbers, but typically when the range got down to 30-40 miles I would plug in the level 2 charger and after a few hours it was up to 60-80, This was consistent with my experience at other times so I assumed that the battery was indeed discharged.
3. press car, select setup, then select factory settings at the bottom of the list. There are options to change specific settings or to reset all to the factory settings, but you have to confirm this choice to avoid blunders.
5. There were substantial temperature changes during the time when this was happening, and my estimated drop of 5-10 miles per day took account of this. When the temperature dropped overnight the charge dropped more, and vice versa. On a couple of occasions the temperature went up overnight but the charge still went down.
6. I do not use my phone or the internet. Everything I have reported is based on sitting in the car and pressing the screen or reading the gauges.

My experience for the past six years is the same as yours, aside from this notable exception. I have left the car for a couple of months sitting in the garage while I was away, with no concern about discharge of either battery. On those occasions I did not record the read-outs before and after, but I have done that on numerous occasions overnight or for a few days, with zero difference in the range except when there were significant temperature changes.
I do not understand how the car could use 7.5-8.5 kWh sitting turned off.

Have you ever replaced the 12 V battery?

You should probably lock the car in the future to be sure it goes into deep sleep. It would also be useful to get an OBD dongle to read the pack voltage.
It might be time to get a new 12 V battery, as maybe that may be leading to unusual draining. I was under the impression that the 12 V battery will not charge if the car is turned off, but now I'm not sure given your strange observations. You should at least check the health of the 12 V battery - I think there is a way you can see that through the center display.
f1geek said:
... You should probably lock the car in the future to be sure it goes into deep sleep. It would also be useful to get an OBD dongle to read the pack voltage.

  • Probably good plan because I hear some kind of coolant pump running frequently just sitting in car without power ON
  • How to learn about the OBD reader? Is it obvious on menu of choices how to find SOC or HV volts?
Nick said:
3. press car, select setup,...

Hey I just thought of battery draining and this menu. Instead of SETUP, try looking in Energy Mgr. At top there's SETTINGS. In here, see if the box for CLIMATE...BATTERY is checked. I've seen this use 2 -3 kWh to heat in winter!

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